title: KRT12 mutations and in vivo confocal microscopy in two Japanese families with Meesmann corneal dystrophy.
abstract: OBJECTIVE
  To identify genetic mutations and study the corneal epithelium in Japanese patients with Meesmann corneal dystrophy.
  
  
  METHODS
  Laboratory investigation and prospective observational case series.
  
  
  METHODS
  Slit-lamp biomicroscopy with fluorescein vital staining and in vivo confocal microscopy were performed. Mutation screening of the KRT3 and KRT12 genes was performed via polymerase chain reaction and direct sequencing for 5 patients in 2 families.
  
  
  RESULTS
  Slit-lamp biomicroscopy revealed multiple corneal intraepithelial microcysts in all patients. A clear zone was seen in the younger generation, whereas mild subepithelial opacity was seen in the older generation. In the in vivo confocal microscopy, numerous corneal intraepithelial microcysts and hyperreflective materials, which were believed to be degenerative cells, were detected closer to the basal layer of the corneal epithelium in older patients. The superficial layer contained more enlarged microcysts, and the hyperreflective materials showed atrophic changes, as compared to the basal layer. The demarcation line between the microcysts and normal epithelial cells was clearly visualized by in vivo confocal microscopy and corresponded to the demarcation line of the clear zone observed by the slit-lamp examination. Two heterozygous mutations (Q130P, L140Q) in the KRT12 gene, one of which (L140Q) was novel, were identified only in the affected patients of the families.
  
  
  CONCLUSIONS
  We identified a novel missense mutation of the KRT12 gene in Meesmann corneal dystrophy. The in vivo confocal microscopy examinations revealed previously unreported depth-dependent ultrastructural changes in the living cornea of Meesmann corneal dystrophy patients.
authors.affiliation: Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan. Electronic address: ogasawara@jikei.ac.jp.
authors.forename: Mikihide
authors.initials: M
authors.lastname: Ogasawara
authors.affiliation: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Hayashi
authors.affiliation: Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Ohno
authors.affiliation: Department of Molecular Genetics, Institute of DNA Medicine, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Yamada
authors.affiliation: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kawakita
authors.affiliation: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan; Department of Ophthalmology, Tokyo Dental College, Ichikawa General Hospital, Chiba, Japan.
authors.forename: Murat
authors.initials: M
authors.lastname: Dogru
authors.affiliation: Department of Ophthalmology, Tokyo Dental College, Ichikawa General Hospital, Chiba, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Shimazaki
authors.affiliation: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tsubota
authors.affiliation: Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsuneoka
mesh_terms: D000293:Adolescent; D000369:Aged, 80 and over; D053559:Corneal Dystrophy, Juvenile Epithelial of Meesmann / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D019573:Epithelium, Corneal / Q000648:ultrastructure; D005260:Female; D019793:Fluorescein / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D006801:Humans; D053551:Keratin-12 / Q000235:genetics*; D018613:Microscopy, Confocal; D008875:Middle Aged; D020125:Mutation, Missense; D010375:Pedigree; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D017422:Sequence Analysis, DNA
chemical_list: D005456:Fluorescent Dyes; C507494:KRT12 protein, human; D053551:Keratin-12; D019793:Fluorescein